<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>

<div class="c1"></div>

请选择性别:
    <input type="radio" name="sex">男
    <input type="radio" name="sex" checked="checked">女
    <input type="radio" name="sex">alex



<script src="jquery.js"></script>
</body>
</html>